Compositional Fluctuations Locked by Athermal Transformation Yielding High Thermoelectric Performance in GeTe.

Yi-Fen Tsai, Pai-Chun Wei, Liuwen Chang, Kuang-Kuo Wang, Chun-Chuen Yang, Yen-Chung Lai, Cheng-Rong Hsing, Ching-Ming Wei, Jian He, G Jeffrey Snyder, Hsin Jay Wu

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Phase transition in thermoelectric (TE) material is a double-edged sword-it is undesired for device operation in applications, but the fluctuations near an electronic instability are favorable. Here, Sb doping is used to elicit a spontaneous composition fluctuation showing uphill diffusion in GeTe that is otherwise suspended by diffusionless athermal cubic-to-rhombohedral phase transition at around 700 K. The interplay between these two phase transitions yields exquisite composition fluctuations and a coexistence of cubic and rhombohedral phases in favor of exceptional figures-of-merit zT. Specifically, alloying GeTe by Sb2 Te3 significantly suppresses the thermal conductivity while retaining eligible carrier concentration over a wide composition range, resulting in high zT values of >2.6. These results not only attest to the efficacy of using phase transition in manipulating the microstructures of GeTe-based materials but also open up a new thermodynamic route to develop higher performance TE materials in general.
Original languageEnglish (US)
Pages (from-to)2005612
JournalAdvanced materials (Deerfield Beach, Fla.)
DOIs
StatePublished - Nov 20 2020

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